氯酸鉀促進龍眼非時開花之效果

Effect of Potassium Chlorate on Off-Season Flowering in Longan

The effect of potassium chlorate (KClO3) on off-season flower induction in 'Fenker' longan (Dimocarpus longan Lour.) was investigated. The percentages of budbreak in KClO3 treated plants were 100% in summer and 70% in autumn substantially higher than those in untreated plants which had 70% budbreak in summer and 6.2% in autumn. KClO3 treatment induced off-season flowering in both seasons. The best result was obtained by applying 2 g KClO3 in solution as soil drenching for each potted experiment plant. The flowering percentages of longan so treated in summer and autumn were 72.5% and 68.9%, respectively. The shoot viability of longan plants was not affected by KClO3 treatment in autumn, but the root viability of the plants 21 days after the KClO3 treatment was lowered. The total nitrogen concentration in the shoot of KClO3 treated plant was not significantly different from that of untreated plants when the chemical was applied in autumn, but was higher when applied in summer. The ethylene production in the shoots of treated plants was not significantly different from that of untreated ones measured throughout the experiment in autumn. The KClO3 did not significantly affect the starch concentration in shoots either in summer or in autumn. In contrast, KClO3 treatment significantly increased the total soluble sugar concentration in shoots when measured 21days after the treatment in summer as well as in autumn. The increase of total soluble sugar in shoots and the reduction of root viability in the treated plants might be the mechanism in enhancing floral induction. 本研究探討氯酸鉀對‘粉殼’龍眼之夏季及秋季非時開花及相關生理變化之影響。氯酸鉀在夏季或秋季處理能誘導產生非時花。各處理中以土壤施用每株2g氯酸鉀之效果最明顯。處理植株在夏季及秋季之萌芽率分別為100%及70.1%，明顯較無處理的70%及6.2%高。處理組夏、秋季的有花率相近，分別為72.5%及68.9%。在秋季施用後枝梢的全氮濃度未見明顯變化，但在夏季施用後則明顯增加。秋季施用後，枝梢之乙烯生成及枝梢之生理活性無顯著影響，但是施用後第21天測定之根生理活性呈現降低。氯酸鉀並未影響兩季枝梢之澱粉濃度，但在施用後第21天測得全可溶性糖增加。由此結果推論氯酸鉀處理促使枝梢之可溶性糖濃度增加及根之生理活性降低，因而誘導花穗的形成。